1. Field of the Invention
The invention relates to a cross-country ski having preferably in its central portion in respect to the length of the ski at least one recess in the sliding surface for at least one interchangeable insert, wherein one surface of said insert is advantageously self-adhesive and the other is preferably provided with means to prevent backward sliding.
2. Description of the Prior Art
Inserts for skis of this type normally comprise several layers, e.g. one layer comprising the means to prevent backward sliding (steps, scales, skin) on the side of the sliding surface, a supporting web, to which the above-mentioned layer is bonded and a band that is adhesive on both of its sides, one side being integrally joined to the supporting web, the other being the self-adhesive surface of the insert. As such an insert is of considerable thickness, a corresponding depth of the recess in the sliding sole of the ski is necessary. In order to achieve this, relatively thick sliding soles must be used, which in the case of cross-country skis is a disadvantage for weight-reasons and/or the cost of the high-quality material for sliding soles. Otherwise, the recesses must extend into the body of the ski, thus impairing the supporting function of the lowest layer of the ski-body, on the one hand and causing problems in the production, on the other hand, as considerable tool-wear is entailed when milling into the lowest supporting layer of the ski, which in the case of modern skis, is almost exclusively made of glass reinforced plastics. It is a further disadvantage that the sliding soles are conventionally produced of materials with poor adhesive qualities, e.g. polyethylene, so that the inserts are not sufficiently affixed to the recesses in such a sliding surface of polyethylene.